1. Field of the Invention
The present invention relates to an air conditioner system for automobiles which is constructed to blow cooled air separately into the front seat space and the rear seat space of a vehicle passenger compartment. More particularly, it relates to such air conditioner system including an improved compressor controller.
2. Prior Art
In recent years, there is a tendency for automotive air conditioner system toward high-grade. Typical examples of such high-grade automotive air conditioner system are shown in Japanese patent publication No. 58-7486 and Japanese patent Laid-open publication No. 57-167819 wherein air passed through an evaporator is blown into a front-seat space and a rear-seat space, separately, under the control of air-mix doors provided respectively for the front-seat and rear-seat spaces to automatically control the temperature of air before the latter is discharged.
According to the foregoing systems, the temperature control of blown-off air is done solely by the air-mix doors without taking the control of a compressor into consideration. In an air conditioner system employing a conventional fixed thermo-control, on-off control of the compressor is effected at a temperature near the freezing point of a refrigerant. With this arrangement, the compressor is much oversized when both the front-seat and rear-seat spaces have small cooling load, resulting in an excess power consumption. Another air conditioner system shown in Japanese Patent Publication No. 58-39083 employs a variable thermo-control for adjusting the on-off temperature of a compressor in accordance with thermal loads either one of the front-seat and rear-seat spaces, and generally with thermal load of the front-seat space. Accordingly, when the front-seat space is smaller in thermal loads than the rear-seat space, the on-off temperature of the compressor becomes high with the result that only an insufficient cooling is achieved at the rear-seat space and conform of occupants therein cannot be maintained.